Long pulse diurnal timer

ABSTRACT

A long pulse diurnal timer for initiating a utilization means, said timer comprising: a coiled bimetal spring having a fixed end and free end, said spring, through its physical expansion, responding to daily sinusoidal changes in temperature via angular displacements at the free end of said spring; a clutch means, said clutch means having its input engagement fixed to the free end of said coiled bimetal spring, said clutch means advancing angularly in response to each daily expansion of said coiled bimetal spring; a pawl means, said pawl means attached to the periphery of said clutch means; a unidirectional ratchet means having an actuation lug, said ratchet means biasingly coupled to said pawl means, said ratchet means being advanced one notch by said pawl means in response to the daily movement of said clutch means; a toggle disk disposed in the path of said actuation lug, said toggle disk being activated only after an advance of a number of ratchet notches corresponding to the angular distance which said actuation lug is initially displaced from said toggle disk, wherein initiation of said utilization means occurs upon activation of said toggle disk.

United States Patent Brown [54] LONG PULSE DIURNAL TIMER [72] Inventor: Donald Brown, Southampton, Pa.

[73] Assignee: The United States of America as represented by the Secretary of the Army [22] Filed: May 25, 1971 [211 App]. No.: 146,765

[52] US. Cl ..337/5l, 337/1 ll [51] Int. Cl. i .J'lOlh 61/00 [58] Field ofSearch ..337l44,61, 81,90, 93, 301,

I FOREIGN PATENTS OR APPLICATIONS 68,969 8/1958 7 France; ..337/81 Primary Examiner-Harold Broome Assistant ExaminerF. E. Bell [451 June 6, 1972 Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Ernest F. Weinberger [57] ABSTRACT A long pulse diurnal timer for initiating a utilization means, said timer comprising: a coiled bimetal spring having a fixed end and free end, said spring, through its physical expansion, responding to daily sinusoidal changes in temperature via angular displacements at the free end of said spring; a clutch means, said clutch means having its input engagement fixed to the free end of said coiled bimetal spring, said clutch means advancing angularly in response to each daily expansion of said coiled bimetal spring; a pawl means, said pawl means attached to the periphery of said clutch means; a unidirectional ratchet means having an actuation lug, said ratchet means biasingly coupled to said pawl means, said ratchet means being advanced one notch by said pawl means in response to the daily movement of said clutch means; a toggle disk disposed in the path of said actuation lug, said toggle disk being activated only after an advance of a number of ratchet notches corresponding to the angular distance which said actuation lug is initially displaced from said toggle disk, wherein initiation of said utilization means occurs upon activation of said toggle disk.

6 Claims, 2 Drawing Figures LONG PULSE DIURNAL TIMER The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION The present invention relates to timers and, more specifically to those timers powered by the output of a bimetallic element that is exposed to changes in temperature.

' A long existent need has been felt for a simply and inexpensively constructed timer capable of accurately initiating an event days or even weeks in the future. Present long-term timers require either, expensive and often unreliable batteries, or complicated timing escapements, and, on occasion, both.

Such timers are utilized in a variety of applications, particularly in the military area. These include a variety of self-arming and self-destruct mechanisms.

The present timing device is wholly mechanical, is self-contained, and is independent of reliance on any electro-chemical battery.

SUMMARY OF THE INVENTION It is well known that temperature variations occur within each day as a result of the effects of darkness and light. Variations also occur as a result of general weather changes which raise. or lower average daily temperatures. However, regardless of this, daily temperature changes will still occur. For example, it is estimated that a minimum variation of F. per day and a maximum of 50 F. per day occur within the temperate zones of the world. If these daily cyclic changes in temperature were to be automatically counted with some device, a basis would be provided for a timer having one pulse count per day. i

This is precisely what the present invention achieves. Hence, it is an object of my invention to provide a means for automatically counting the daily changes in temperature and to therein provide a basis for powering a long-term timer.

Another object is to provide a long-term timer that can be simply and inexpensivelyconstructed. i

A further object is to provide a low cost, self-powered, longlife, automatically initiating timer that does not require maintenance.

, The present invention comprises: a coiled bimetal spring having a fixed end and free end, said spring, through its physical expansion, responding to daily sinusoidal changes in temperature via angular displacements at the free end of said spring; a clutch means, said clutch means having its input engagement fixed to the free end of said coiled bimetal spring, said clutch means advancing angularly in response to each daily expansion of said coiled bimetal spring; a pawl means,

said pawl means attached to the periphery of said clutch means; a unidirectional ratchet means having an actuation lug, said ratchet means biasingly coupled to said pawl means, said ratchet means being advanced one notch by said pawl means in response to the daily movement of said clutch means; a toggle disk disposed in the path of said actuation lug, said toggle disk being activated only after an advance of a number of ratchet notches corresponding to the angular distance which I said actuation lug is initially displaced from said toggle disk,

wherein initiation of said utilization means occurs upon activation of said toggle disk.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exploded assembly perspective view of a timer made in accordance with the principles of the present invention.

FIG. 2 is a cut-away side view of the novel device scaled to actual size.

DETAILED DESCRIPTION OF THE INVENTION The present long pulse diurnal timer utilizes classical engineering principles in that it depends solely on the forces of nature for its operation.

Central to the operation of this diurnal timer is a coiled bimetal spring element 10 (see FIG. 1). This bimetallic element is used to sense temperature variations in a similar manner to those used in dial thermometers and thermostats. A bimetallic element responsive to temperature changes in the l0 to 50 F. range is required for the present application.

One end 12 of the spring element 10 is fixed to a case 14a, b, as by rivet means 16. The other end 18, being bent, is fixed to a slip clutch 20 by means of a notch 22 on said clutch. The clutch remains free to move in either direction, under the movement of the element end 18, as dictated by rising and falling temperatures. 7

A shaft 24 serves as an axle for said clutch 20 and a slotted clutch plate 26. Said plate is equipped with a lateral slotted flange 28 that rides about a pin 30 that is fixed to the base 14b. Said flange 28, coacting with pin 30, limits the angular travel of the clutch plate 26 to an angular displacement representing the maximum expected temperature variation within a given day. Travel exceeding this limit causes the clutch 20 to slip. The clutch 20 also permits the timer to adjust automatically to any new temperature level without affecting the temperature increment required to operate the device.

The output of the slotted clutch plate 26 advances a pawl driver 32 which is attached to the periphery of said clutch plate. Said pawl driver 32 then engages a ratchet wheel 34, whose teeth are directed for unidirection motion. Also shown in FIG. I is a pressure spring 35 which establishes a biased fit between the pawl driver and the ratchet wheel.

As a result of the fact that the daily variations in temperature are generally sinusoidal in nature, the bimetallic spring 10 will, on the average, advance the ratchet wheel 34 one notch during each 24 hour period. Hence, it is seen that the ratchet wheel provides a means for accumulating the daily notch pulses wherein each day's pulse adds one notch to the previous total.

In order to obviate possible clockwise slippage of the ratchet wheel 34, a tooth-type pawl-stop 42 is affixed to the interior of case 14.

Attached to and carried by the ratchet wheel 34 is a fixed lug which serves as an actuation lug 36. Said lug progresses forward with each pulse until contact is made with a toggle disk 38. Disk 38 is connected to wires 40 which in turn are connected to either a self-destruct mechanism or any other utilization means intended to be activated after days or even weeks of lying inactive.

A particular time setting can be achieved by moving the actuation lug 36 and the ratchet wheel 34 therewith, clockwise to the desired number of notch pulses away from the toggle disk 38, e.g., seven notches away from the toggle disk 38 represents the seven days required for actuation to occur.

It should be kept in mind that the present diurnal timer is intended for long time-period applications. Such a timer set for one day would be inaccurate in that the daily temperature change may occur within a small portion of the 24 hour period. However, on the assumption that only one cycle occurs each day (even though it may occur during a portion of the day and remain constant for the balance), a timer set for 7 days could function in 6 and a fraction days, i.e., something less than 7 days. It set for 30 days, it could then function in 29 and a fraction days. It can be seen that as a one day timer, its accuracy would be marginal, but that its accuracy improves exponentially as a function of longer time settings.

FIG. 2 illustrates an assembled timer scaled to actual size.

It is thus seen from the above that the objects set forth'are among those made apparent from, and efficiently attained by, the device of the preceding description.

I wish it to be understood that I do not desire to be limited to the exact detail of construction shown and described for obvious modification will occur to persons skilled in the art.

Having described my invention, what I claim as new, useful and non-obvious, and thus desire to secure by Letters Patent of the United States is:

l. A long pulse diurnal timer for initiating a utilization means, said timer comprising:

a coiled bimetal spring, having a fixed end and a free end, said spring, through its physical expansion, responding to daily sinusoidal changes in temperature via angular displacements at the free end of said spring;

a clutch means, said clutch means having its input engagement fixed to the free end of said coiled bimetal spring, said clutch means advancing angularly in response to each daily expansion of said coiled bimetal spring;

a pawl means, said pawl means attached to the periphery of said clutch means;

a unidirectional ratchet means having an actuation lug, said ratchet means biasingly coupled to said pawl means, said ratchet means being advanced one notch by said pawl means in response to the daily movement of said clutch means;

a toggle disk disposed in the path of said actuation lug, said toggle disk being activated only after an advance of a number of ratchet notches corresponding to the angular distance which said actuation lug is initially displaced from said toggle disk,

wherein initiation of said utilization means occurs upon activation of'said toggle disk.

2. The timer of claim 1 wherein said clutch means comprises:

a shaft, said shaft providing axial support for said clutch means;

a slip clutch, said slip clutch engaging said free end of said cooled bimetal spring, wherein said slip clutch will slip when the angular displacement of said free end of said spring exceeds a pre-determined displacement; and

a clutch plate, said plate having said pawl means attached to its periphery.

3. The timer of claim 2, said timer further including slotted means carried by said plate and coacting with limit means for limiting the angular displacement of said plate.

4. The timer of claim 3, said timer having a cover proximately encasing it, said cover comprising said limit means.

5. The timer of claim 4, wherein the interior of said cover further includes a unidirectional stop for engaging said ratchet means and thereby preventing angular slippage of said ratchet wheel in a non-advancing direction.

6. The timer of claim 5, said timer having a biasing means axially centered between said clutch plate and said ratchet wheel, said biasing means providing a yielding engagement between said clutch plate and said ratchet wheel. 

1. A long pulse diurnal timer for initiating a utilization means, said timer comprising: a coiled bimetal spring, having a fixed end and a free end, said spring, through its physical expansion, responding to daily sinusoidal changes in temperature via angular displacements at the free end of said spring; a clutch means, said clutch means having its input engagement fixed to the free end of said coiled bimetal spring, said clutch means advancing angularly in response to each daily expansion of said coiled bimetal spring; a pawl means, said pawl means attached to the periphery of said clutch means; a unidirectional ratchet means having an actuation lug, said ratchet means biasingly coupled to said pawl means, said ratchet means being advanced one notch by said pawl means in response to the daily movement of said clutch means; a toggle disk disposed in the path of said actuation lug, said toggle disk being activated only after an advance of a number of ratchet notches corresponding to the angular distance which said actuation lug is initially displaced from said toggle disk, wherein initiation of said utilization means occurs upon activation of said toggle disk.
 2. The timer of claim 1 wherein said clutch means comprises: a shaft, said shaft providing axial support for said clutch means; a slip clutch, said slip clutch engaging said free end of said cooled bimetal spring, wherein said slip clutch will slip when the angular displacement of said free end of said spring exceeds a pre-determined displacement; and a clutch plate, said plate having said pawl means attached to its periphery.
 3. The timer of claim 2, said timer further including slotted means carried by said plate and coacting with limit means for limiting the angular displacement of said plate.
 4. The timer of claim 3, said timer having a cover proximately encasing it, said cover comprising said limit means.
 5. The timer of claim 4, wherein the interior of said cover further includes a unidirectional stop for engaging said ratchet means and thereby preventing angular slippage of said ratchet wheel in a non-advancing direction.
 6. The timer of claim 5, said timer having a biasing means axially centered between said clutch plate and said ratChet wheel, said biasing means providing a yielding engagement between said clutch plate and said ratchet wheel. 